WACKER Presents New High-Performance Silicones and Polymeric Binders for the Plastics and Bioplastics Industry

“In many sectors, for example in the automotive and lighting industries, material requirements are constantly on the rise, and conventional materials such as organic plastics are slowly reaching their limits. That’s why many developers increasingly tend to opt for innovative materials, for example silicones,” says Peter Summo, head of the Engineering Silicones business unit at WACKER, to explain the rising demand for this cutting-edge polymer based on elemental silicon. “Silicones are resistant to high mechanical and thermal stress, chemicals, and UV-radiation. And, above all, they are highly versatile. This enables them to cope with rising requirements significantly better than conventional materials,” continues Summo. Processability is another important advantage of these all-rounders, he adds. “Silicones have excellent processing properties. High-quality molded parts can be produced extremely cost-efficiently.”

Another of the company’s key topics at K 2013 is an improved binder for the next generation of bioplastics. VINNEX® makes it possible to develop higher-performance biopolymer blends, whose property profiles can be tailored better to both application and demand, so that a more diverse range of applications and processing techniques can be tapped. “This example illustrates how diversely WACKER is positioned at this year’s K tradeshow,” Peter Summo stresses. “Our product portfolio not only offers innovative solutions for silicone processors and their customers, but also for plastics and bioplastics processors.”

Extra thin and Immaculate: ELASTOSIL Film
At K 2013, WACKER will be introducing a world first: precision silicone films. Marketed as ELASTOSIL® Film, this product is available as roll stock in thicknesses down to 20 microns. It is manufactured in cleanroom conditions without the use of solvents. For improved handling, ELASTOSIL® Film comes with an inter- mediate backing from which they can easily be peeled off intact.

WACKER’s patent-registered production process provides immaculate and extremely uniform silicone films with a defined thickness. The film thickness across the entire width and length of the film web deviates from the specification by ±5 percent at most. This particular property, together with the material’s typical silicone characteristics, permits technical applications that were previously very hard or even impossible to implement on an industrial scale.

Silicone films can be used to manufacture gas-permeable packaging and protective films, membranes for separating or enriching gases or particularly soft and flexible woundcare plasters. Because silicone elastomers are electrically insulating, have good dielectric properties, and endure long-term mechanical loads with hardly any signs of fatigue, ELASTOSIL® Film can also be used, for example, as an electroactive polymer (EAP). Under certain conditions, EAPs are able to alter their shape when a voltage is applied. As a result, silicon films can be used to design innovative sensors, actuators and generators. Potential applications range from toys, electrical relays and electrically operated valves to artificial limbs and peristaltic pumps.

Magnetic: ELASTOSIL® R 781/80
ELASTOSIL® R 781/80 is a silicone rubber filled with tiny magnetic particles. The particles – roughly ten micrometers in size – are made of ferrimagnetic magnetite material, which are firmly integrated into the silicone rubber matrix. The silicone compounds are capable of being magnetized in the presence of a strong magnetic or electromagnetic field. Together with other magnets, this magnetic effect is particularly pronounced.

The new silicone elastomere offers diverse application possibilities. For example, ELASTOSIL® R 781/80 enables the manufacturing of magnetic components and profiles. They not only adhere to flat, but also to curved or rounded metallic surfaces. As silicones elastomers are also known for their very good extrusion behavior, profiles thus can be manufactured very efficiently and in virtually all lengths and shapes. The cured silicone is extremely heat-resistant and withstands temperatures ranging from –40 °C to +200 °C with ease.

The highly filled silicone elastomer contains 70% w/w magnetite and has an 80 Shore A hardness. The ingredients used are in compliance with the recommendations of the German Federal Institute for Risk Assessment (BfR, XV. Silicones, IX. Colorants) and the US Food and Drug Administration (FDA). The product is therefore suitable for applications involving contact with food. ELASTOSIL® R 781/80 can be processed directly, or else compounded with other silicones prior to further processing. This opens up even more potential applications, especially within the food, packaging and medical-technology sectors.

Coolant resistant: ELASTOSIL® LR 3022/60

Standard silicone elastomers are not really suitable as sealants in the hot areas of engine cooling circuits. As soon as such standard elastomers come into contact with a coolant of over 100 degrees Celsius in temperature – usually a water/glycol mixture – some of their key properties for leak-tightness, such as elasticity and high resilience, deteriorate.

At K 2013, WACKER will, for the first time, present a silicone rubber for making seals fully suited for cooling systems. The addition-cure liquid silicone rubber, ELASTOSIL® LR 3022/60, features a very low compression set. The silicone rubber’s lasting resilience ensures consistently high leak-tightness in the seal groove. Furthermore, the overall property profile of cured ELASTOSIL® LR 3022/60 rubber remains virtually unchanged under long-term load. As a result, molded parts made of the new silicone grade can be used as seals or gaskets even when they are directly exposed to hot coolants.

In addition, the silicone rubber exhibits very good low-temperature flexibility down to -45 degrees Celsius. With this combination of temperature and coolant resistance, ELASTOSIL LR 3022/60 offers an alternative to organic elastomers.

Extremely heat resistant: ELASTOSIL® R 756

The outstanding feature of these peroxide-curing solid silicone rubber grades is the excellent heat resistance of the vulcanized product. Depending on the heat stabilizer added during compounding, the vulcanizates can withstand long term temperatures of 250 °C, medium term up to 300 °C. This makes these new silicone grades ideal for use in self-cleaning ovens and stoves or in automotive applications such as the engine compartment.

ELASTOSIL® R 756 solid silicone rubber grades are designed in such a way that their excellent properties unfold by interaction with the heat stabilizers added to the base rubber during the compounding process. The thermal stability of the vulcanizate is influenced by the type and amount of the chosen stabilizer. The new grades can be processed via compression molding, injection molding or extrusion. The latter method, however, requires the use of a suitable heat stabilizer that is compatible with the crosslinker. WACKER offers ELASTOSIL® R 756 both as a base rubber blend without additives and as a ready-to-process compound that already contains effective heat stabilizers.

Highly transparent – LUMISIL® LR 7600

The new LUMISIL® LR 7600 product range consists of liquid silicone rubber grades that cure to form highly transparent elastomers. The cured rubber grades are crystal clear and can withstand high thermal stress. Unlike highly transparent thermoplastics such as polycarbonate and polymethyl methacrylate, LUMISIL® LR 7600 does not tend to yellow. The cured rubber remains colorless even at high temperatures and under long-term exposure to artificial or natural light, including ultraviolet radiation. The elastomers are resistant to aging and weathering, electrically insulating, water-repellent and low- temperature flexible.

This property set fulfills all material requirements that play a key role in the manufacture of optical elements. Lens bodies made of LUMISIL® LR 7600 can direct and shape a lamp’s light, for example. In combination with light emitting diodes (LEDs), entirely new designs and housing structures are possible. Furthermore, the product enables the development of energy- and cost-efficient solutions, for example in general lighting and car headlights

Thanks to their excellent thermal stability, optical components made of LUMISIL® LR 7600 can be combined with xenon lamps and high- performance LEDs. These types of lamps increasingly find use in headlights of cars and get very hot in continuous operation. In adaptive headlight systems, optical elements made of LUMISIL®

LR 7600 can help to ensure that the road is optimally illuminated under any traffic conditions.

Further Highlights

• VINNEX® – Enhanced Binder System for Bioplastics VINNEX® is an improved binder system for the next generation of bioplastics. It enables polymers based on renewable raw materials to be processed just like conventional thermoplastics. The system enhances the physical properties of bioplastics and makes different materials compatible with each other. Depending on the composition and VINNEX® content, polymer blends have higher impact strengths, are more flexible or have a higher melt strength than conventional biopolymers. VINNEX® opens up an expanding range of applications for biopolymers. For example, the new blends can be processed into food packaging materials, brochures, parts for electronic appliances or self-degradable gardening and agricultural containers.

• ELASTOSIL® R 752 – Solid Silicones with Excellent Damping Properties for Automotive and Mechanical Engineering

The two new silicones solid silicone rubber grades ELASTOSIL®
R 752/30 and ELASTOSIL® R 752/70 complement the existing ELASTOSIL® R 752 product range. They cure to form elastomers that are significantly less elastic than standard silicone rubber. As a result, they have a strong damping effect on shocks and undesired vibrations. At the same time, they possess all the typical properties of silicones, such as heat resistance, low-temperature flexibility and aging resistance. Thus, ELASTOSIL® R 752 is ideal for making the vibration dampers that are needed in automotive engineering, in particular.

• ELASTOSIL® R 416 – High Consistency Silicone for Hose Extrusion

The new grade of high consistency silicone rubber ELASTOSIL® R 416/70 features very high green strength. The product enables cost-effective production of fabric-reinforced silicone hoses by extrusion. Hoses made from ELASTOSIL® R 416/70 are ideal for automotive applications requiring good temperature and coolant resistance.

• ELASTOSIL® Tin-Free System for Condensation Curing Mold Making Compounds

ELASTOSIL® Tin-Free System was designed for all base components of ELASTOSIL® M condensation curing moldmaking compounds and consists of a tin-free catalyst plus booster. Compounds cured with the system can be processed normally and possess the same mechanical properties as compounds cured with standard catalysts. Since its application is not subject to legal restrictions, ELASTOSIL® Tin-Free System represents a practical alternative to conventional, tin-based systems.

• POWERSIL® 570 PLUS – Solvent-free Silicone Coating for T&D Insulators

POWERSIL® 570 PLUS is a new silicone coating for electrical insulators. The solvent-free one-component emulsion serves to coat glass or porcelain insulators. The product is sprayed on glass or porcelain parts and then cures to form a water-repellent silicone coating. The coating considerably increases the reliability and fail- safe characteristics of insulators for transmission and distribution (T&D) substations and overhead power lines.

• GENIOPLAST® Pellet P Plus – All-Purpose Silicone Additive for Food Contact Plastics

GENIOPLAST® Pellet P plus is a high-performance additive for the compounding and processing of thermoplastics. It improves the viscosity and flow properties of the polymer compound, allowing the compound to be processed more efficiently and at lower cost. It also ensures smooth, easy-to-clean surfaces. GENIOPLAST®

Pellet P plus is an approved additive for plastics used in food contact applications and is therefore suitable for plastics in the kitchen and packaging sector.